Climate change is turning Antarctica green

The lockdown may be easing carbon dioxide emissions, but climate change is still making huge changes to the planet.

New research has found the Antarctic coast is set to turn green because of algal blooms so vast they can be seen from space.

Scientists from the University of Cambridge created the first ever large-scale map of microscopic algae as they bloomed across the surface of snow along the coastline of Antarctica.

Their findings suggest that ‘green snow’ is likely to spread further and faster as global temperatures increase.

Researchers from Cambridge and the British Antarctic Survey combined satellite data with on-the-ground observations from over two summers spent at the South Pole detecting and measuring green snow algae.

The study, published in journal Nature Communications, shows that – although each individual alga is microscopic in size – they turn the snow bright green and can be seen from space when grown en masse.

Study leader Dr Matt Davey, from the University of Cambridge’s Department of Plant Sciences, said: ‘This is a significant advance in our understanding of land-based life on Antarctica, and how it might change in the coming years as the climate warms.

‘Snow algae are a key component of the continent’s ability to capture carbon dioxide from the atmosphere through photosynthesis.’

Blooms of green snow algae are found around the Antarctic coastline, particularly on islands along the west coast of the Antarctic Peninsula.

They grow in ‘warmer’ areas, where average temperatures are just above zero degrees Celsius during the austral summer – the Southern Hemisphere’s summer months of November to February.

The Peninsula is the part of Antarctica that experienced the most rapid warming in the latter part of the last century.

Scientists found that the distribution of green snow algae is strongly influenced by birds and mammals, whose excrement acts as a highly nutritious natural fertiliser. Over 60 per cent of blooms were found within five kilometres of a penguin colony.

Algae were also observed growing near the nesting sites of other birds – including skuas – and areas where seals come ashore.

Dr Davey said: ‘We identified 1679 separate blooms of green algae on the snow surface, which together covered an area of 1.9 kilometres squared, equating to a carbon sink of around 479 tonnes per year.

This is the equivalent amount of carbon emitted by roughly 875,000 car journeys in the UK.

Almost two thirds of the green algal blooms were on small, low-lying islands with no high ground.

As the Antarctic Peninsula warms due to rising global temperatures, these islands may lose their summer snow cover – and with it their snow algae.

However the majority of snow algae is found in a small number of larger blooms in the north of the Peninsula and the South Shetland Islands, in areas where they can spread to higher ground as low-lying snow melts.

Lead author Dr Andrew Gray, from the University of Cambridge, said: ‘As Antarctica warms, we predict the overall mass of snow algae will increase, as the spread to higher ground will significantly outweigh the loss of small island patches of algae.’